The use of imaging devices or other sensors during in-flight operations of aerial vehicles is increasingly common. In particular, unmanned aerial vehicles, or UAVs, are frequently equipped with one or more imaging devices such as digital cameras, range cameras, depth sensors, infrared sensors or other systems that may detect, capture and/or process visible or invisible light. Where an aerial vehicle is equipped with one or more imaging devices, such devices may be utilized in any number of operations or applications of the aerial vehicle, and for any purpose. For example, an imaging device may be used to capture imaging data such as still or moving images and any associated audio signals or metadata to aid in the safe operation of an aerial vehicle, e.g., for maneuvering or control. An imaging device carried aboard an aerial vehicle may be used in monitoring applications, such as when the aerial vehicle is utilized to photograph large or diverse areas, or areas from angles that cannot readily be accessed by grounded photographers or ground-based photographic equipment.
Many imaging devices are operated using automatic exposure algorithms, in which one or more attributes of the cameras are controlled to optimize the exposure of an image based on one or more attributes of a previously captured image. An image may be processed to generate a histogram of pixel brightness or intensities, e.g., a graphical representation of numbers of pixels having specific brightness or intensity levels. To the extent that the histogram indicates that the image is overexposed, or underexposed, an exposure time, a gain, an aperture, or one or more other attributes of the imaging device or variables associated with its operation may be adjusted to optimize a level of quality of a next image captured by the imaging device based on the histogram.
Where an imaging device is provided aboard an operating aerial vehicle or another structure, which may be stationary or in motion, contents of images captured by the imaging device vary from image to image as contents of a field of view of the imaging device change, due to motion or changes in orientation of the aerial vehicle or structure.